the direction indicated by the arrows. The inner, average, and outer radii of the donut are indicated
by r 1 , r 2 , and r 3 , respectively. What is the magnitude and direction of the magnetic field at point
P , the center of the donut?(A) zero(B) (C)
(D)
(E)
23 . A wire carries a current toward the top of the page. An electron is located to the right of the wire,
as shown above. In which direction should the electron be moving if it is to experience a magnetic
force toward the wire?
(A) into the page
(B) out of the page
(C) toward the bottom of the page
(D) toward the top of the page
(E) to the right24 . Which of the following statements about electric and magnetic fields is FALSE:
(A) A charge moving along the direction of an electric field will experience a force, but a charge
moving along the direction of a magnetic field will not experience a force.
(B) All charges experience a force in an electric field, but only moving charges can experience a
force in a magnetic field.
(C) A positive charge moves in the direction of an electric field; a positive charge moves
perpendicular to a magnetic field.
(D) All moving charges experience a force parallel to an electric field and perpendicular to a
magnetic field.
(E) A negative charge experiences a force opposite the direction of an electric field; a negative
charge experiences a force perpendicular to a magnetic field.